Fetal monitoring is a valuable tool for monitoring and assessing fetal status and labor progress during pregnancy and childbirth. While there are various types of monitors, all monitor the same signals and assess fetal well-being by measuring parameters such as fetal heart rate and observing the effect of maternal influences, such as labor contractions, on the baby's heart rate. In the modern hospital environment of today, monitoring is most often done electronically.
There are two types of electronic monitoring methods: internal and external. Internal monitoring involves affixing a transducer to the baby's scalp to monitor heart rate, and an intrauterine pressure catheter to monitor contractions. Internal monitoring can only be used after the cervix is dilated at least two centimeters. Because of this, internal monitoring cannot be used during preterm or early labor and is generally used only after signs of fetal distress are observed through an external monitoring method.
The conventional external electronic fetal monitor is a two-belt ultrasound device that is strapped about the mother's abdomen. One belt holds a listening device (e.g., an acoustic signal transducer) in place while the other belt holds the contraction monitor (e.g., a pressure signal transducer). The nurse or midwife frequently must adjust the belts to get the best readings from each device. The response of the baby's heartbeat to uterine contractions is used to determine the baby's health and well-being. For example, a deceleration or drop in fetal heart rate following a contraction may indicate that the baby is not getting enough oxygen, an early sign of possible fetal distress. One or both of the transducers may be used intermittently or continuously during labor. Frequently the transducers are used intermittently during early labor and continuously during later stages of labor. In addition, mothers hospitalized for preterm labor and pregnancy complications often must wear the external fetal monitor continuously for extended periods.
The present method for external fetal monitoring, using circumferential belts to position the heart rate and uterine contraction transducers, has several distinct disadvantages. For example, the belts limit the mobility of the mother since movement by the mother frequently causes the positions of the belts and transducers to shift, thereby causing the loss of one or both of the signals. The loss of the fetal heartbeat signal due to movement of the transducer may cause an alarm on the monitor to sound requiring the attention of a clinician and causing anxiety to the mother. Often the mother must remain relatively motionless, in a more or less prone position, a circumstance that both increases patient discomfort and slows the progress of labor. Each time a transducer is dislodged by patient movement, a nurse or other clinician must hunt around with the transducer to find a “sweet spot” in which a clear signal is obtained and adjust the associated belt to keep the transducer in this position. This happens frequently during labor. Also, as the baby often changes position, the transducer location must also be changed to obtain a suitable signal. This repositioning of the transducer requires an associated repositioning of the appropriate belt, an operation which frequently causes discomfort for the mother.
If the monitor is being used intermittently, it is necessary to apply and remove the associated belts from the mother, again causing discomfort. In addition, some patients have a shape which does not allow transducers to be reliably positioned on their abdominal region using the current belt system. Accordingly, there is a need for an improved system and method for positioning and retaining monitoring transducers on a patient. The present invention addresses that need.